EP0011559B1 - Process and apparatus for wet attrition - Google Patents

Process and apparatus for wet attrition Download PDF

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Publication number
EP0011559B1
EP0011559B1 EP79400847A EP79400847A EP0011559B1 EP 0011559 B1 EP0011559 B1 EP 0011559B1 EP 79400847 A EP79400847 A EP 79400847A EP 79400847 A EP79400847 A EP 79400847A EP 0011559 B1 EP0011559 B1 EP 0011559B1
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Prior art keywords
tank
stirring
fact
pulp
members
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German (de)
French (fr)
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EP0011559A1 (en
Inventor
Jean-Louis Cardini
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Societe Le Nickel SLN SA
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Societe Metallurgique Le Nickel SLN SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B7/00—Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • B01F27/90—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with paddles or arms 
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap

Definitions

  • the present invention relates to an attrition process which is implemented in a wet environment and which is more particularly suitable for the allocation of already ground ores. It also relates to a device for implementing this method.
  • wet attrition consists in subjecting mineral grains which are dispersed in water to friction and shock whose energy is too weak to produce a grinding, but nevertheless sufficient to release the most tender fractions, these are found in the aqueous phase in the form of very fine particles: attrition not only makes it possible to separate the tender particles, but also generates new particles due to friction and interparticle shocks.
  • Attrition a different technique, which is also called attrition, but this is not intended to create new particles. This is particularly the case in the glass industry where a so-called attrition technique is used for settling the sands: only separation is sought here.
  • Documents FR-A-2 381 108 and FR-A-2 320 781 describe a process for the preconcentration of metalliferous products or nickel ores consisting in subjecting the starting product to gentle attrition after grinding and prior pulping, controlled attrition being obtained by simple agitation of the pulp, then to carry out at least one classification.
  • An object of the present invention is to provide an attrition process which allows not only the separation of the soft fraction of the ore, but also the creation of new very fine particles.
  • An object of the invention is a process of this type which results in lower energy consumption than that of known attrition processes.
  • This object and this object, as well as others which will appear subsequently, are achieved by a wet attrition process of ores previously crushed to a size between 30 and 0.4 mm, put into pulp and subjected to a simple agitation in a slightly turbulent medium, characterized by the fact that the value of the Reynolds number of the medium is between 1,000 and 5,000, the agitation being carried out by means of at least one pair of agitation organs consisting of an upper stirring member and a lower stirring member whose lift coefficients are substantially constant over the entire length, the stirring members being such that the upper member induces a downward flow of pulp while the lower organ causes an upward flow of pulp, so that the two flows meet in the middle zone located between the two organs of the couple.
  • the dryness of the pulp is at least equal to 50% and even greater than 70%, and is preferably between 65% and 78% .
  • the present invention also relates to a device for the implementation of this method, device which comprises a tank of circular or polygonal section with at least six sides, an axial agitator provided with at least a couple of stirring members substantially horizontal, one of which is an upper agitator and the other of which is a lower agitator, an injection pipe as well as a recovery pipe, opening into the tank as close as possible to the axial agitator, characterized in that the agitating members have a substantially constant lift coefficient over their entire length, the upper and lower agitating members being such that, when the axis is rotated, the upper member induces a downward flow of pulp while that the lower organ causes an upward flow of pulp, so that the two flows meet in the median zone located between the two organs of the couple.
  • agitating members have a substantially constant lift coefficient over their entire length, that is to say that the volume flow rate per surface element is constant regardless of the position of this element within the area defined by the rotating mobile.
  • the ratio between the section of the tank and the surface of the circle generated by the rotation of the stirring members is between 1.7 and 2.4 and, preferably, between 1.9 and 2.1.
  • the vertical distance between two stirring members of the same couple is between 0.3 and 0.7 times, and preferably between 0.4 and 0.6 times, the diameter of the circle generated by the rotation of these members .
  • the vertical distance between the lower stirring member of a couple and the bottom of the tank is substantially equal to a quarter of the diameter of the circle generated by the rotation of these stirring members.
  • the distance between the upper member of a pair and the top of the tank it is advantageously substantially equal to half the diameter of the circle generated by the rotation of these stirring members.
  • each stirring member consists of three horizontal blades mounted at 120 ° from each other.
  • the device according to the present invention comprises a cylindrical tank 1 provided with an axial agitator 2 comprising an axis 5 on which is mounted a pair of agitating members 3 and 4 which are substantially horizontal.
  • the tank has a ratio between its height and its diameter of between 0.7 and 1.5, and preferably between 0.9 and 1.2.
  • the polyhedral tank has 10 to 12 sides.
  • Particularly suitable stirring members are those whose lift coefficient is constant over their entire length, and which induce identical average speeds of flow through the pulp flow whatever the position of this flow on the stirring member. Such a structure thus makes it possible to minimize the turbulence which is not necessary to achieve attrition and which entails an unnecessary consumption of energy.
  • the stirring members 3 and 4 each consist of three blades, 3a, 3b, 3c and 4a, 4b, 4c, respectively, which are mounted at 120 °, as shown in Figure 2.
  • These stirring members can be arranged so that the axis of the blade 3a is in the same vertical plane as that, for example, of the blade 4a.
  • the ratio between the free surface of the tank 1 and the surface described by the blades is between 1.7 and 2.4, and preferably between 1.9 and 2.1. According to an advantageous embodiment, this ratio is equal to 2.
  • the diameter of the inscribed circle must be taken into account.
  • the vertical distance between the two stirring members 3 and 4 is between 0.3 and 0.7 times, preferably between 0.4 and 0.6 times the diameter of the circle that they generate during their rotation.
  • the vertical distance between the bottom 7 of the tank 1 and the lower stirring member, indicated by the reference 4 in Figure 1, is equal to about half the diameter of the circle generated by the stirring members in rotation.
  • This bottom 7 can be flat or concavity directed upwards, which improves the circulation of the pulp in the tank.
  • a garnieritic nickel ore is introduced through a conduit 6 which opens at the center of the bottom 7 of the tank 1.
  • the dryness of this pulp that is to say the percentage of dry matter thereof, must be at least equal to 50% and even be greater than 70% as far as possible.
  • the ore itself it must have an optimal particle size for the type of ore treated: thus, a particle size distribution such that 80% of the particles pass through a sieve whose meshes have a size between 250 microns and 3 millimeters is considered satisfactory in this case.
  • the pulp is propelled, on the one hand, upwards by the lower member 4, and, on the other hand, downwards by the upper member 3: therefore, the mineral particles meet and collide with each other. against each other in an area located approximately halfway between the two stirring members 3 and 4.
  • the treated pulp is collected by a conduit 8 which opens in the center of the cover 9 of the tank 1. We can then either introduce it into another tank to undergo a new attrition cycle, or direct it towards other facilities.
  • the pulp flows by overflow along a cone 10 which covers the tank 1 and is collected in a gutter 11 located around the upper part of this tank.
  • the pipe 8 can be used to introduce the pulp into the tank 1, the treated pulp then flowing through the pipe 6 under the effect of the forces of gravity.
  • the pulp has to undergo another attrition cycle, this can take place in an independent tank. dante. However, this additional cycle can also be carried out in a second tank superimposed on the first, as shown in FIG. 3, the pulp circulating in an ascending manner.
  • the first attrition tank is designated by C and by C 'this upper tank.
  • the assembly has a ratio between the total height and the diameter of between 1.2 and 3, and preferably between 1.8 and 2.4.
  • a partition 12 in the center of which opens downward a cylindrical conduit 13 possibly provided with baffles which surrounds without contact the rotary axis 5.
  • This conduit 13 which is located in the space of the tank C, allows the pulp to pass from this tank C to the tank C '.
  • the length of this cylindrical conduit 13 is such that it enters the vortex created by agitation in the tank C.
  • the tank C ′ also comprises a pair of stirring members 15 and 16 identical to that of the cell C.
  • the elements similar to those of FIG. 1 have the same reference.

Abstract

This invention provides a process and apparatus for the wet attrition of ore. The process comprises grinding the ore to a pulp having a particle size distribution such that about 80% by weight of the particles have a diameter of from about 30 to about 0.4 mm; and agitating the pulp in a slightly turbulent medium. The apparatus comprises a vat having top and bottom covers with central openings and a gutter disposed along the exterior circumference of the top of the vat; a cylindrical shaft extending through the opening in the top cover; and a pair of impellers mounted at a distance apart on the shaft, the blades of the impellers being so arranged that the pulp is pumped towards the space defined between the two impellers.

Description

La présente invention concerne un procédé d'attrition qui est mis en oeuvre en milieu humide et qui est plus particulièrement adapté à l'attribution de minerais déjà broyés. Elle concerne également un dispositif pour la mise en oeuvre de ce procédé.The present invention relates to an attrition process which is implemented in a wet environment and which is more particularly suitable for the allocation of already ground ores. It also relates to a device for implementing this method.

L'attrition par voie humide consiste à soumettre des grains minéraux qui sont dispersés dans de l'eau à des frottements et à des chocs dont l'énergie est trop faible pour produire un broyage, mais cependant suffisante pour libérer les fractions les plus tendres, celles-ci se retrouvant dans la phase aqueuse sous forme de particules très fines : l'attrition, non seulement permet de séparer les particules tendres, mais également engendre de nouvelles particules du fait des frottements et des chocs interparticulaires.Wet attrition consists in subjecting mineral grains which are dispersed in water to friction and shock whose energy is too weak to produce a grinding, but nevertheless sufficient to release the most tender fractions, these are found in the aqueous phase in the form of very fine particles: attrition not only makes it possible to separate the tender particles, but also generates new particles due to friction and interparticle shocks.

Certaines industries mettent en oeuvre, actuellement, une technique différente, qui est aussi appelée attrition, mais celle-ci ne vise nullement à la création de nouvelles particules. C'est notamment le cas dans l'industrie de la verrerie où l'on utilise une technique dite d'attrition pour le débourbage des sables : seule une séparation est ici recherchée.Some industries are currently implementing a different technique, which is also called attrition, but this is not intended to create new particles. This is particularly the case in the glass industry where a so-called attrition technique is used for settling the sands: only separation is sought here.

De plus, ces techniques improprement dites d'attrition ne donnent pas de résultats satisfaisants quand on veut traiter des matériaux comme par exemple un minerai de nickel. En outre, elles sont grandes consommatrices d'énergie. Ainsi dans le cas de l'attrition de produits métallifères, par exemple d'un minerai garniéritique de nickel, l'application de ces techniques connues entraîne une dépense de 80 kilowatts par tonne de minerai traité pour obtenir un rendement de 30 % en poids de particules créées par l'attrition.In addition, these improperly called attrition techniques do not give satisfactory results when it is desired to treat materials such as, for example, a nickel ore. In addition, they are large consumers of energy. Thus in the case of the attrition of metalliferous products, for example of a garnierite ore of nickel, the application of these known techniques involves an expenditure of 80 kilowatts per ton of ore treated to obtain a yield of 30% by weight of particles created by attrition.

Les documents FR-A-2 381 108 et FR-A-2 320 781 décrivent un procédé de préconcentration de produits métallifères ou de minerais nickélifères consistant a soumettre le produit de départ à une attrition ménagée après broyage et mise en pulpe préalable, l'attrition ménagée étant obtenue par simple agitation de la pulpe, puis à procéder à au moins un classement.Documents FR-A-2 381 108 and FR-A-2 320 781 describe a process for the preconcentration of metalliferous products or nickel ores consisting in subjecting the starting product to gentle attrition after grinding and prior pulping, controlled attrition being obtained by simple agitation of the pulp, then to carry out at least one classification.

Un but de la présente invention est de fournir un procédé d'attrition qui permet, non seulement la séparation de la fraction tendre du minerai, mais aussi la création de nouvelles particules très fines.An object of the present invention is to provide an attrition process which allows not only the separation of the soft fraction of the ore, but also the creation of new very fine particles.

Un objet de l'invention est un procédé de ce type qui entraîne une consommation énergétique inférieure à celle des procédés d'attrition connus.An object of the invention is a process of this type which results in lower energy consumption than that of known attrition processes.

Ce but et cet objet, ainsi que d'autres qui apparaîtront par la suite, sont atteints par un procédé d'attrition humide de minerais préalablement broyés à une dimension comprise entre 30 et 0,4 mm, mis en pulpe et soumis à une simple agitation en milieu peu turbulent, caractérisé par lé fait que la valeur du nombre de Reynolds du milieu est comprise entre 1 000 et 5 000, l'agitation étant réalisée au moyen d'au moins un couple d'organes d'agitation constitué d'un organe d'agitation supérieur et d'un organe d'agitation inférieur dont les coefficients de portance sont sensiblement constants sur toute la longueur, les organes d'agitation étant tels que l'organe supérieur induit un flux de pulpe vers le bas tandis que l'organe inférieur provoque un flux de pulpe vers le haut, de manière que les deux flux se rencontrent dans la zone médiane située entre les deux organes du couple.This object and this object, as well as others which will appear subsequently, are achieved by a wet attrition process of ores previously crushed to a size between 30 and 0.4 mm, put into pulp and subjected to a simple agitation in a slightly turbulent medium, characterized by the fact that the value of the Reynolds number of the medium is between 1,000 and 5,000, the agitation being carried out by means of at least one pair of agitation organs consisting of an upper stirring member and a lower stirring member whose lift coefficients are substantially constant over the entire length, the stirring members being such that the upper member induces a downward flow of pulp while the lower organ causes an upward flow of pulp, so that the two flows meet in the middle zone located between the two organs of the couple.

Le nombre de Reynolds est défini par la formule suivante :

Figure imgb0001
dans laquelle

  • U = vitesse de rotation du mobile, t/mn ;
  • d = diamètre du mobile, cm ;
  • p = densité de la pulpe, gm/cm3 ; et
  • µ = viscosité de la pulpe, centipoise.
The Reynolds number is defined by the following formula:
Figure imgb0001
 in which
  • U = mobile rotation speed, rpm;
  • d = diameter of the mobile, cm;
  • p = density of the pulp, gm / cm 3 ; and
  • µ = viscosity of the pulp, centipoise.

Avantageusement, la siccité de la pulpe, c'est-à-dire le pourcentage de matière sèche de celle-ci, est au moins égale à 50 % et même supérieure à 70 %, et est de préférence comprise entre 65 % et 78%.Advantageously, the dryness of the pulp, that is to say the percentage of dry matter thereof, is at least equal to 50% and even greater than 70%, and is preferably between 65% and 78% .

La présente invention a également pour objet un dispositif pour la mise en oeuvre de ce procédé, dispositif qui comprend une cuve de section circulaire ou polygonale à au moins six côtés, un agitateur axial muni d'au moins un couple d'organes d'agitation sensiblement horizontaux dont l'un est un agitateur supérieur et l'autre un agitateur inférieur, une conduite d'injection ainsi qu'une conduite de récupération, débouchant dans la cuve au plus près de l'agitateur axial, caractérisé par le fait que les organes d'agitation ont un coefficient de portance sensiblement constant sur toute leur longueur, les organes d'agitation supérieur et inférieur étant tels que, lorsque l'axe est mis en rotation, l'organe supérieur induit un flux de pulpe vers le bas tandis que l'organe inférieur provoque un flux de pulpe vers le haut, de manière que les deux flux se rencontrent dans la zone médiane située entre les deux organes du couple.The present invention also relates to a device for the implementation of this method, device which comprises a tank of circular or polygonal section with at least six sides, an axial agitator provided with at least a couple of stirring members substantially horizontal, one of which is an upper agitator and the other of which is a lower agitator, an injection pipe as well as a recovery pipe, opening into the tank as close as possible to the axial agitator, characterized in that the agitating members have a substantially constant lift coefficient over their entire length, the upper and lower agitating members being such that, when the axis is rotated, the upper member induces a downward flow of pulp while that the lower organ causes an upward flow of pulp, so that the two flows meet in the median zone located between the two organs of the couple.

Ces organes d'agitation ont un coefficient de portance sensiblement constant sur toute leur longueur, c'est-à-dire que le débit volumique par élément de surface est constant quelle que soit la position de cet élément à l'intérieur de l'aire définie par le mobile en rotation.These agitating members have a substantially constant lift coefficient over their entire length, that is to say that the volume flow rate per surface element is constant regardless of the position of this element within the area defined by the rotating mobile.

Le rapport entre la section de la cuve et la surface du cercle engendré par la rotation des organes d'agitation est compris entre 1,7 et 2,4 et, de préférence, entre 1,9 et 2,1.The ratio between the section of the tank and the surface of the circle generated by the rotation of the stirring members is between 1.7 and 2.4 and, preferably, between 1.9 and 2.1.

La distance verticale entre deux organes d'agitation d'un même couple est comprise entre 0,3 et 0,7 fois, et de préférence entre 0,4 et 0,6 fois, le diamètre du cercle engendré par la rotation de ces organes.The vertical distance between two stirring members of the same couple is between 0.3 and 0.7 times, and preferably between 0.4 and 0.6 times, the diameter of the circle generated by the rotation of these members .

De préférence, la distance verticale entre l'organe d'agitation inférieur d'un couple et le fond de la cuve est sensiblement égale au quart du diamètre du cercle engendré par la rotation de ces organes d'agitation.Preferably, the vertical distance between the lower stirring member of a couple and the bottom of the tank is substantially equal to a quarter of the diameter of the circle generated by the rotation of these stirring members.

Quant à la distance entre l'organe supérieur d'un couple et le sommet de la cuve, elle est, avantageusement, sensiblement égale à la moitié du diamètre du cercle engendré par la rotation de ces organes d'agitation.As for the distance between the upper member of a pair and the top of the tank, it is advantageously substantially equal to half the diameter of the circle generated by the rotation of these stirring members.

Selon un mode de réalisation préféré, chaque organe d'agitation est constitué par trois pales horizontales montées à 120° les unes des autres.According to a preferred embodiment, each stirring member consists of three horizontal blades mounted at 120 ° from each other.

La description qui va suivre et qui ne présente aucun caractère limitatif permettra de bien comprendre comment la présente invention peut être mise en pratique. Elle doit être lue en regard des figures annexées, parmi lesquelles :

  • la figure 1 représente, en coupe longitudinale, un dispositif selon l'invention ;
  • la figure 2 représente ce même dispositif en coupe transversale selon la ligne AA de la figure 1 ;
  • la figure 3 montre, en coupe longitudinale, comment deux dispositifs selon l'invention peuvent être disposés.
The description which follows and which does not have any limiting character will make it possible to understand clearly how the present invention can be put into practice. It should be read in conjunction with the appended figures, among which:
  • Figure 1 shows, in longitudinal section, a device according to the invention;
  • 2 shows this same device in cross section along the line AA of Figure 1;
  • Figure 3 shows, in longitudinal section, how two devices according to the invention can be arranged.

Ainsi qu'on peut le voir sur la figure 1, le dispositif selon la présente invention comprend une cuve cylindrique 1 munie d'un agitateur axial 2 comportant un axe 5 sur lequel est monté un couple d'organes d'agitation 3 et 4 qui sont sensiblement horizontaux. La cuve présente un rapport entre sa hauteur et son diamètre compris entre 0,7 et 1,5, et de préférence entre 0,9 et 1,2.As can be seen in FIG. 1, the device according to the present invention comprises a cylindrical tank 1 provided with an axial agitator 2 comprising an axis 5 on which is mounted a pair of agitating members 3 and 4 which are substantially horizontal. The tank has a ratio between its height and its diameter of between 0.7 and 1.5, and preferably between 0.9 and 1.2.

Au lieu d'une cuve cylindrique, on peut utiliser une cuve polyédrique dont le nombre de faces doit être supérieur ou égal à six. De préférence, la cuve polyédrique possède de 10 à 12 côtés.Instead of a cylindrical tank, one can use a polyhedral tank whose number of faces must be greater than or equal to six. Preferably, the polyhedral tank has 10 to 12 sides.

Des organes d'agitation convenant particulièrement sont ceux dont le coefficient de portance est constant sur toute leur longueur, et qui induisent des vitesses moyennes de traversée du flux de pulpe identiques quelle que soit la position de ce flux sur l'organe d'agitation. Une telle structure permet ainsi de minimiser les turbulences qui ne sont pas nécessaires pour réaliser l'attrition et qui entraînent une consommation superflue d'énergie.Particularly suitable stirring members are those whose lift coefficient is constant over their entire length, and which induce identical average speeds of flow through the pulp flow whatever the position of this flow on the stirring member. Such a structure thus makes it possible to minimize the turbulence which is not necessary to achieve attrition and which entails an unnecessary consumption of energy.

Selon ce mode de réalisation, les organes d'agitation 3 et 4 sont chacun constitués de trois pales, 3a, 3b, 3c et 4a, 4b, 4c, respectivement, qui sont montées à 120°, comme représenté sur la figure 2. Ces organes d'agitation peuvent être disposés de telle sorte que l'axe de la pale 3a soit dans le même plan vertical que celui, par exemple, de la pale 4a.According to this embodiment, the stirring members 3 and 4 each consist of three blades, 3a, 3b, 3c and 4a, 4b, 4c, respectively, which are mounted at 120 °, as shown in Figure 2. These stirring members can be arranged so that the axis of the blade 3a is in the same vertical plane as that, for example, of the blade 4a.

Comme exemple de telles pales, on peut citer celles fabriquées et commercialisées par la firme S.E.M. (Société Européenne de Mélanges) sous la dénomination commerciale « SABRE ».As an example of such blades, mention may be made of those manufactured and marketed by the firm S.E.M. (Société Européenne de Mélanges) under the trade name "SABER".

Lorsque l'axe 5 est en rotation, le rapport entre la surface libre de la cuve 1 et la surface décrite par les pales est compris entre 1,7 et 2,4, et préférentiellement entre 1,9 et 2,1. Selon un mode de réalisation avantageux, ce rapport est égal à 2.When the axis 5 is in rotation, the ratio between the free surface of the tank 1 and the surface described by the blades is between 1.7 and 2.4, and preferably between 1.9 and 2.1. According to an advantageous embodiment, this ratio is equal to 2.

Si la cuve est polyédrique, il faut prendre en considération le diamètre du cercle inscrit.If the tank is polyhedral, the diameter of the inscribed circle must be taken into account.

La distance verticale entre les deux organes d'agitation 3 et 4 est comprise entre 0,3 et 0,7 fois, de préférence entre 0,4 et 0,6 fois le diamètre du cercle qu'ils engendrent lors de leur rotation.The vertical distance between the two stirring members 3 and 4 is between 0.3 and 0.7 times, preferably between 0.4 and 0.6 times the diameter of the circle that they generate during their rotation.

La distance verticale entre le fond 7 de la cuve 1 et l'organe d'agitation inférieur, indiqué par le repère 4 sur la figure 1, est égale à environ la moitié du diamètre du cercle engendré par les organes d'agitation en rotation. Ce fond 7 peut être plan ou à concavité dirigée vers le haut, ce qui améliore la circulation de la pulpe dans la cuve.The vertical distance between the bottom 7 of the tank 1 and the lower stirring member, indicated by the reference 4 in Figure 1, is equal to about half the diameter of the circle generated by the stirring members in rotation. This bottom 7 can be flat or concavity directed upwards, which improves the circulation of the pulp in the tank.

Quant à la distance verticale entre l'organe d'agitation supérieur 3 et le couvercle 9 de la cuve 1, elle est sensiblement égale à celle existant entre les deux organes d'agitation 3 et 4.As for the vertical distance between the upper stirring member 3 and the cover 9 of the tank 1, it is substantially equal to that existing between the two stirring members 3 and 4.

En fonctionnement, on introduit un minerai garniéritique de nickel par un conduit 6 qui débouche au centre du fond 7 de la cuve 1. La siccité de cette pulpe, c'est-à-dire le pourcentage de matière sèche de celle-ci, doit être au moins égale à 50 % et être même supérieure à 70 % dans la mesure du possible. Quant au minerai lui- même, il doit présenter une granulométrie optimale pour le type de minerai traité : ainsi, une distribution granulométrique telle que 80% des particules passent à travers un tamis dont les mailles ont une taille comprise entre 250 microns and 3 millimètres est jugée satisfaisante dans ce cas.In operation, a garnieritic nickel ore is introduced through a conduit 6 which opens at the center of the bottom 7 of the tank 1. The dryness of this pulp, that is to say the percentage of dry matter thereof, must be at least equal to 50% and even be greater than 70% as far as possible. As for the ore itself, it must have an optimal particle size for the type of ore treated: thus, a particle size distribution such that 80% of the particles pass through a sieve whose meshes have a size between 250 microns and 3 millimeters is considered satisfactory in this case.

La pulpe est propulsée, d'une part, vers le haut par l'organe inférieur 4, et, d'autre part, vers le bas par l'organe supérieur 3: de ce fait, les particules minérales se rencontrent et se heurtent les unes contre les autres dans une zone située environ à mi-distance entre les deux organes d'agitation 3 et 4.The pulp is propelled, on the one hand, upwards by the lower member 4, and, on the other hand, downwards by the upper member 3: therefore, the mineral particles meet and collide with each other. against each other in an area located approximately halfway between the two stirring members 3 and 4.

On recueille la pulpe traitée par un conduit 8 qui s'ouvre au centre du couvercle 9 de la cuve 1. On peut alors, soit l'introduire dans une autre cuve pour subir un nouveau cycle d'attrition, soit la diriger vers d'autres installations.The treated pulp is collected by a conduit 8 which opens in the center of the cover 9 of the tank 1. We can then either introduce it into another tank to undergo a new attrition cycle, or direct it towards other facilities.

Selon le mode de réalisation représenté sur la figure 1, la pulpe s'écoule par débordement le long d'un cône 10 qui coiffe la cuve 1 et est recueillie dans une gouttière 11 située autour de la partie supérieure de cette cuve.According to the embodiment shown in Figure 1, the pulp flows by overflow along a cone 10 which covers the tank 1 and is collected in a gutter 11 located around the upper part of this tank.

On peut également pomper la pulpe traitée à l'aide d'un conduit débouchant dans la cuve aussi près que possible de l'axe de rotation 5.It is also possible to pump the treated pulp using a pipe opening into the tank as close as possible to the axis of rotation 5.

Le conduit 8 peut être utilisé pour introduire la pulpe dans la cuve 1, la pulpe traitée s'écoulant alors par la conduite 6 sous l'effet des forces de gravité.The pipe 8 can be used to introduce the pulp into the tank 1, the treated pulp then flowing through the pipe 6 under the effect of the forces of gravity.

Ainsi, dans le cas d'un minerai garniéritique de nickel, et en utilisant une cuve de 5 m3, on a obtenu un rendement d'attrition de l'ordre de 30 % avec une consommation de puissance de 15 kilowatts par tonne de minerai traité, alors que les dispositifs d'attrition connus entraînent une consommation de l'ordre de 80 kilowatts par tonne de minerai traité.Thus, in the case of a garnieritic nickel ore, and by using a 5 m 3 tank, an attrition yield of the order of 30% was obtained with a power consumption of 15 kilowatts per tonne of ore treated, while the known attrition devices entail a consumption of the order of 80 kilowatts per tonne of ore treated.

Comme il a été dit précédemment, dans le cas où la pulpe doit subir un autre cycle d'attrition, celui-ci peut avoir lieu dans une cuve indépendante. Mais ce cycle supplémentaire peut également être réalisé dans une seconde cuve superposée à la première, comme représenté sur la figure 3, la pulpe circulant de façon ascendante. On a désigné par C la première cuve d'attrition et par C' cette cuve supérieure. L'ensemble présente un rapport entre la hauteur totale et le diamètre compris entre 1,2 et 3, et de préférence entre 1,8 et 2,4.As mentioned above, if the pulp has to undergo another attrition cycle, this can take place in an independent tank. dante. However, this additional cycle can also be carried out in a second tank superimposed on the first, as shown in FIG. 3, the pulp circulating in an ascending manner. The first attrition tank is designated by C and by C 'this upper tank. The assembly has a ratio between the total height and the diameter of between 1.2 and 3, and preferably between 1.8 and 2.4.

Entre les deux cuves d'attrition C et C' est disposée une cloison 12 au centre de laquelle s'ouvre vers le bas un conduit cylindrique 13 éventuellement muni de chicanes qui entoure sans contact l'axe rotatif 5. Ce conduit 13, qui est situé dans l'espace de la cuve C, permet de faire passer la pulpe de cette cuve C à la cuve C'. La longueur de ce conduit cylindrique 13 est telle qu'il pénètre dans le vortex créé par l'agitation dans la cuve C.Between the two attrition tanks C and C 'is disposed a partition 12 in the center of which opens downward a cylindrical conduit 13 possibly provided with baffles which surrounds without contact the rotary axis 5. This conduit 13, which is located in the space of the tank C, allows the pulp to pass from this tank C to the tank C '. The length of this cylindrical conduit 13 is such that it enters the vortex created by agitation in the tank C.

La cuve C' comprend également un couple d'organes d'agitation 15 et 16 identiques à celui de la cellule C. Sur la figure 3, les éléments analogues à ceux de la figure 1 portent la même référence.The tank C ′ also comprises a pair of stirring members 15 and 16 identical to that of the cell C. In FIG. 3, the elements similar to those of FIG. 1 have the same reference.

Les distances verticales entre l'organe d'agitation supérieur 3 et la cloison 12 d'une part, et entre la cloison 12 et l'organe d'agitation inférieur 15 d'autre part, sont identiques à celles décrites dans le cas de la cuve unique représentée sur la figure 1.The vertical distances between the upper stirring member 3 and the partition 12 on the one hand, and between the partition 12 and the lower stirring member 15 on the other hand, are identical to those described in the case of the single tank shown in Figure 1.

A la suite d'une étude expérimentale, le résultat empirique suivant a pu être dégagé : lorsqu'un minerai est finement broyé, c'est-à-dire que les grains ont un diamètre inférieur à un millimètre, et lorsque la quantité et la nature des fines produites au cours de l'attrition entraînent une élévation importante de la viscosité des pulpes, celles-ci présentant un comportement rhéologique de caractère pseudo-plastique, il est opportun d'induire une circulation particulière, telle que décrite plus haut, pour de telles pulpes si l'on veut qu'une partie importante du produit à attri- tionner circule au travers des organes d'agitation et ne soit pas alors éliminée par débordement : ce qui aurait pour conséquence de diminuer notablement le rendement d'attrition.Following an experimental study, the following empirical result could be obtained: when an ore is finely ground, that is to say that the grains have a diameter less than one millimeter, and when the quantity and the nature of the fines produced during attrition lead to a significant increase in the viscosity of the pulps, these having a rheological behavior of pseudo-plastic character, it is advisable to induce a particular circulation, as described above, to such pulps if a large part of the product to be attracted is to circulate through the stirring members and is not then eliminated by overflowing: this would have the consequence of significantly reducing the attrition yield.

C'est pourquoi dans le cas du minerai de nickel cité plus haut comme exemple, il est nécessaire que les conduits d'introduction et de récupération soient situés au plus près de l'agitateur axial.This is why in the case of the nickel ore mentioned above as an example, it is necessary that the introduction and recovery conduits are located as close as possible to the axial agitator.

Les spécialistes en la matière comprendront que le procédé et le dispositif selon l'invention permettent de réaliser notamment la préconcentration des minerais nickélifères oxydés d'origine latéritique, comme décrit dans le brevet français n° 2320781, ou la préconcentration de produits métallifères, comme décrit dans le brevet français n° 2381 108.Specialists in the field will understand that the method and the device according to the invention make it possible in particular to carry out the preconcentration of oxidized nickel ores of lateritic origin, as described in French patent n ° 2320781, or the preconcentration of metalliferous products, as described in French patent n ° 2381 108.

Claims (11)

1. Wet attrition process for ores previously crushed to a size comprised between 30 and 0.4 mm, pulped and subjected to simple stirring in a slightly turbulent medium, characterised by the fact the value of the reynolds number of the medium is comprised between 1000 and 5000, the stirring being effected by means of at least one pair of stirring members consisting of a top stirring member (3) and a bottom stirring member (4) whose lift coefficients are substantially constant over their whole length, the stirring members being such that the top member induces a downward flow of pulp while the bottom member causes an upward flow of pulp, so that the two flows meet in the median area situated between the two members of the pair.
2. Process according to claim 1, characterised by the fact that the value of the Reynolds number is comprised between 2 000 and 4 000.
3. Process according to one of claims 1 and 2 characterised by the fact that, in a way known in itself, the dryness of the pulp is at least 50 %.
4. Process according to claim 3, characterised by the fact that the dryness of the pulp exceeds 70 % and is preferably comprised between 70 and 78%.
5. Device for implementing the process according to one of the foregoing claims 1 to 4, comprising a tank (1) whose section is circular or polygonal with at least six sides, an axial agitator (2) fitted with at least one pair of substantially horizontal stirring members (3, 4) one of which is a top agitator (3) and the other a bottom agitator (4), an injection pipe (6) giving into the tank (1) at the point closest to the axial agitator (2), as well as a recovery pipe (8), characterised by the fact that the stirring members (3, 4) have a substantially constant lift coefficient over their whole length, the top (3) and bottom (4) stirring members being such that, when the shaft (5) is rotated, the top member induces a downward flow of pulp while the bottom member causes an upward flow of pulp, so that the two flows meet in the median area situated between the two members of the pair.
6. Device according to claim 5, characterised by the fact that the mean speed of passage across a stirring member (3, 4) by an hydraulic flow is constant irrespective of the position of this flow in the horizontal plane defined by the rotation of the said stirring member (3, 4).
7. Device according to one of claims 5 to 6 such that the ratio of the section of the tank (1) to the area of the circle generated by the rotation of the stirring members (3, 4) is at least 1.7 and that the vertical distance between the two stirring members (3, 4) of one and the same pair, which is substantially equal to the vertical distance separating the lid (9) of the tank (1) from the top stirring member (3) of the pair in the top position in the tank (1), is comprised between 0.3 and 0.7 times, and preferably between 0.4 and 0.6 times the diameter of the circle generated by the rotation of the stirring members (3, 4), characterised by the fact that the ratio of the section of the tank (1) to the area of the circle generated by the rotation of the stirring members (3, 4) is comprised between 1.9 and 2.4, and preferably between 1.9 and 2.1.
8. Device according to one of claims 5 to 7, characterised by the fact that the vertical distance between the bottom (7) of the tank (1) and the bottom stirring member (4) of the pair situated in the bottom position in the tank (1) is substantially equal to half of the diameter of the circle generated by the rotation of the stirring members (3, 4).
9. Device according to one of claims 5 to 8, characterised by the fact that, in a way known in itself, the stirring members (3, 4) comprise three horizontal blades (4a, 4b, 4c) mounted at 120° on the said axial agitator (2).
10. Device according to one of claims 5 to 9, characterised by the fact that it comprises two attrition tanks (C, C') positioned one on top of the other, between which there is a partition (12) in the centre of which a cylindrical pipe (13) leads downwards, surrounding without touching a rotating shaft (5) of a common agitator (2) and on which are mounted the two stirring members (3, 4) of a bottom pair positioned in the bottom tank (C), below the partition (12), and the two stirring members (15, 16) of a top pair positioned in the top tank (C') above the partition (12).
11. Device according to claim 10, characterised by the fact that the cylindrical pipe (13) is of such a length that it penetrates into the vortex created by the stirring in the bottom tank (C).
EP79400847A 1978-11-15 1979-11-12 Process and apparatus for wet attrition Expired EP0011559B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79400847T ATE10861T1 (en) 1978-11-15 1979-11-12 METHOD AND DEVICE FOR CRUSHING MINERALS BY WET WAY.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7832217A FR2441425A1 (en) 1978-11-15 1978-11-15 METHOD AND DEVICE FOR WET ATTRACTION
FR7832217 1978-11-15

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EP0011559A1 EP0011559A1 (en) 1980-05-28
EP0011559B1 true EP0011559B1 (en) 1984-12-19

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JP (1) JPS55124553A (en)
AT (1) ATE10861T1 (en)
AU (1) AU537854B2 (en)
BR (1) BR7907421A (en)
CA (1) CA1151624A (en)
DE (1) DE2967335D1 (en)
FR (1) FR2441425A1 (en)
GR (1) GR74068B (en)
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OA (1) OA06385A (en)
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JPH0352108Y2 (en) * 1987-03-27 1991-11-11
US4930576A (en) * 1989-04-18 1990-06-05 Halliburton Company Slurry mixing apparatus
SE503898C2 (en) * 1994-10-25 1996-09-30 Tetra Laval Holdings & Finance Mixer for mixing liquids or suspensions and mixing process
NL1002649C2 (en) * 1996-03-19 1997-09-22 Coen Hendrik Decnop Mixing device.
US5964527A (en) * 1997-03-19 1999-10-12 Decnop; Coen Hendrik Mixing device
FI112096B (en) * 2001-07-06 2003-10-31 Omg Finland Oy Process for the extraction of nickel and possibly cobalt by leaching from nickel-containing laterite ore
US20050221246A1 (en) * 2003-10-31 2005-10-06 Dan Drinkwater Apparatus and method for liberating deleterious material from fine aggregate
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CN101823059B (en) * 2009-03-05 2012-01-04 中国恩菲工程技术有限公司 Laterite washing equipment
CA2967880C (en) 2016-05-20 2023-03-21 Superior Industries, Inc. Aggregate attrition systems, methods, and apparatus
USD873305S1 (en) 2017-05-19 2020-01-21 Superior Industries, Inc. Attrition mill propeller
CN108262144B (en) * 2018-01-24 2019-09-06 泉州台商投资区万鼎机械科技有限公司 Integrated Chinese medicine intelligence milling apparatus
CN114174547A (en) * 2019-07-31 2022-03-11 杰富意钢铁株式会社 High-strength steel sheet for acid-resistant line pipe, method for producing same, and high-strength steel pipe using high-strength steel sheet for acid-resistant line pipe

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FR2320781A1 (en) * 1975-08-14 1977-03-11 Nickel Sln Ste Metallurg Le PROCESS FOR PRECONCENTRING NICKEL-OXIDIZED OXIDES OF LATERITIC ORIGIN
DE2616155A1 (en) * 1976-04-13 1977-10-27 Karl Heinz Dipl Ing Meller WET GRINDING DEVICE
FR2381108A1 (en) * 1977-02-16 1978-09-15 Minemet Rech Sa PROCESS FOR THE PRECONCENTRATION OF METALLIC PRODUCTS

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US4434942A (en) 1984-03-06
AU537854B2 (en) 1984-07-19
MA18639A1 (en) 1980-07-01
EP0011559A1 (en) 1980-05-28
YU278279A (en) 1983-02-28
DE2967335D1 (en) 1985-01-31
JPH0160297B2 (en) 1989-12-21
OA06385A (en) 1981-07-31
GR74068B (en) 1984-06-06
FR2441425A1 (en) 1980-06-13
BR7907421A (en) 1980-07-08
CA1151624A (en) 1983-08-09
AU5280179A (en) 1980-05-22
PT70454A (en) 1979-12-01
ATE10861T1 (en) 1985-01-15
JPS55124553A (en) 1980-09-25

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